As an electric motor having a cooling function, there are conventionally known one disclosed in Patent Literatures 1 and 2. An electric motor of this type includes a casing having a peripheral wall, which is internally formed with a cooling channel. The cooling channel allows a cooling medium such as water or oil to flow therein to thereby cool the casing.
It is important for an electric motor having such a cooling function to improve the cooling function, especially, a function of cooling a stator which generates heat, while restricting the structure of the electric motor from upsizing.